Emery (1890) described the first two taxa in the complex. Aphaenogaster phalangiumHNS was described first, based on a syntype worker and male from "Alajuela, Jimenez." The worker was described as having a shiny fourth abdominal tergite, and the illustration showed somewhat convex neck and a non-tuberculate propodeum. Aphaenogaster araneoidesHNS was described from a syntype worker, also from "Alajuela, Jimenez." It was described as having an opaque gaster, and the illustration shows a tapered neck and a tuberculate propodeum. The published locality data for both species, "Alajuela, Jimenez," is a composite of two collecting localities frequented by Anastasio Alfaro, who sent the material to Emery. Alajuela is a city in the Central Valley of Costa Rica, and is the likely source of the phalangiumHNS workers. Jimenez is a small town in the Atlantic lowlands very near La Selva Biological Station, and is the likely source of the A. araneoidesHNS workers. The senior author examined the syntypes at MCSN in 1990. Under A. araneoidesHNS were (1) a pin with one worker, labeled "Alajuela", and a "Typus" label; and (2) a pin with two workers and an "Alajuela" label. Under A. phalangiumHNS were (1) a pin with one worker, labeled "Costa Rica, Alfaro", and with a "Typus" label; (2) a pin with two workers and a "Costa Rica, Alfaro" label, (3) a pin with one worker and an "Alajuela, Alf." label; and (4) a pin with a male labeled "Jimenez." The types were examined before the significance of leg pilosity was understood, and the status of this character was not recorded. However, the worker material under A. araneoidesHNS had tapered necks, opaque abdominal tergites, and tuberculate propodeums, while the workers under A. phalangiumHNS had convex necks, shiny abdominal tergites, and non-tuberculate propodeums. The MCZC has a pin with two workers, labeled " Ischnomyrma phalangium EmHNS, Costa Rica. from Emery." The specimens and the label look like part of the A. phalangiumHNS syntype series, and the specimens have pilose femora. We suspect there were labeling errors, and that all the A. phalangiumHNS syntype workers were from one collection from Alajuela, and all the A. araneoidesHNS syntype workers and the one A. phalangiumHNS syntype male were from one collection from Jimenez. We have requested that the MCSN add labels to these specimens with the suggested corrections. For A. araneoidesHNS and A. phalangiumHNS we have selected the single workers with Emery's "typus" labels as the lectotypes.

Borgmeier's (1949) description of the male was based on two specimens from Hamburg Farm, a site in the Atlantic lowlands of Costa Rica, where A. araneoidesHNS is almost certainly the ony species present.

The syntypes of Forel's A. brevicollisHNS come close to bridging the gap between A. araneoidesHNS and A. phalangiumHNS. The workers are quite robust, there is a row of about five setae on the posterior border of the mesepisternum, the pilosity is abundant and coarse (approaching the more pilose condition of A. phalangiumHNS), and the fourth abdominal tergite is smooth and shining. The pilosity on the hind femur is relatively coarse compared to other A. araneoidesHNS and yet is clearly appressed on the dorsal surface and strongly contrasting with all known A. phalangiumHNS workers.